1. Field of the Invention
The present invention relates to an imaging system capable of improving the quality of image data obtained by taking an optical image of a subject, an imaging apparatus including the imaging system, a portable terminal apparatus including the imaging system, an onboard apparatus including the imaging system, a medical apparatus including the imaging system, and a method for manufacturing the imaging system.
2. Description of Related Art
An imaging system is well known that forms an optical image of a subject through an imaging lens on a light receiving surface of an imaging device, such as a CCD or a CMOS device, having a set of two-dimensionally arrayed plurality of light receiving pixels.
As an example of such an imaging system, an onboard camera or a portable cellular phone camera having an imaging lens designed such that the depth of field increases is attached directly on a circuit board has already put to practical use (refer to JP-A-2007-147951). In addition, an onboard camera or a portable cellular phone camera with high performance is also known in which the number of pixels of an imaging device is increased so that the resolving power of an imaging system is improved. Among such onboard cameras or portable cellular phone cameras with high performance which are capable of obtaining high-resolution images, it is also known that the resolving power of an imaging system is already close to a diffraction limited.
However, in manufacturing an imaging system having such an imaging lens capable of forming a high resolution image, it is difficult to increase the yield due to difficulties in manufacture. This would cause a possibility that many imaging systems will be out of a production line for readjustment or reassembly since image data cannot be generated which allow an output image to have an intended resolution. In addition, an imaging system removed from the production line is reproduced such that image data can be generated in order to be capable of forming an image with an intended resolution after specifying the cause and modification accordingly.
However, there are various causes of reducing the output resolution from an imaging system. For example, various causes, such as shape errors (surface shape error, thickness error, and de-centering error of surfaces) of an individual lens used to form an imaging lens, assembly and adjustment errors of an imaging lens (shift error and tilt error of a lens and air space error between lenses), and a positional error of an imaging device with respect to an imaging lens, may be considered. For this reason, there is a problem that a cost would be significantly increased for reproduction in order for an imaging system to be capable of generating high-quality image data, which allows an output image to have an intended resolution, by specifying a cause of the reduction in resolution and performing readjustment and reassembly.